Topical preparations in the form of analgesics are widely used to relieve pain. They are typically used by consumers with muscle or joint pains, soreness, sprains or strains, and are used by consumers unable to tolerate oral analgesics, for example users who suffer from ulcers or who are pregnant, or consumers desiring topical analgesia as an adjunct to oral medication. Topical analgesics typically come in the form of ointments, lotions, solutions and creams that are applied to the affected area. They relieve the pain and stiffness of arthritis, rheumatism, muscle and joint soreness, back pain, bursitis, tendonitis, muscle strains and sprains, bruises and cramps. In more recent years, topical analgesics have been administered via adhesive patches, particularly in cases of back aches and soreness.
Although topical analgesics are effective in providing prompt pain relief, their effect is not always long lasting. Some topical analgesics must be reapplied often because the effect wears off quickly. Topical analgesics may also be rubbed off during daily activities or wiped off by the rubbing of clothes against the affected area. Recently, patches consisting of topical analgesics have been used to realize longer lasting pain relief, such as described in U.S. Pat. No. 6,277,401, which teaches a patch for drug delivery through a foam layer. Many other topical analgesic patches are simply a layer of adhesive impregnated with a topical analgesic formulation and a layer of gauze or other fabric. These patches apply the active ingredients in the form of a semi-flexible patch that holds the analgesic and protects it from being worn off during daily activities. Although usually having longer efficacy than topical application of creams and ointments, the analgesic patches only minimally extend release of the active ingredients and so the effectiveness of the analgesic wears off quickly. Moreover, the patches have a number of draw backs. Consumers do not like the feel of the patches because they feel wet, often have strong menthol odors, and do not adhere well to joints. The application of the patches can also be difficult. Additionally, the patches do not stay in place, except when used on flat body areas such as the back, which are not subject to substantial movements or flexing actions. Finally, use of the patches on hirsute body areas may result in additional pain due to unintended hair extraction when the patch is removed.
Despite the existence of topical analgesic creams, lotions and sticks and topical analgesics in the form of patches in the prior art, there is room for improvement. None of the prior art discloses employing a micro-vesicle system for administration of the active ingredients in order to provide for extended release of the active ingredient resulting in more effective treatment. Use of the micro-vesicle technology may also reduce the wet and soggy feeling associated with the application of analgesic patches, because less ointment is required to achieve the desired effect. Moreover, the prior art does not disclose the use of topical analgesics in the form of sleeves or joint-specific applications so that the topical preparation stays in place through the full range of motion and repeated bending of a joint, and without the requirement of an adhesive to hold the patch in place.
A variety of methods are currently used to administer topical analgesics for pain relief. The methods typically involve the topical administration of analgesics to the affected area. Some products are administered in the form of creams, lotions, ointments and sticks. Although these products provide faster and more localized pain relief than the oral administration of drugs, the relief may be short lived if the analgesic is not long lasting or wears off quickly. Other products include patches impregnated with topical or external analgesics that are applied to the target area. Although these products provide longer lasting pain relief by holding the active ingredients, patches still do not provide substantially extended release of active ingredients and do not suitably adhere to joint areas. Removal of adhesive patches may also produce consumer discomfort. A more effective and long lasting method of administering these products is needed.
The current invention consists of a product for topical administration of extended release substances for relieving pain. The invention comprises micro-encapsulation of one or more active ingredients to provide extended release of the active ingredient in the form of a cream, lotion, ointment or stick. Alternatively, the invention may be in the form of a flexible patch or sleeve, or joint specific application, providing an extended release active formulation.